In today's Curious Cook column I write about the elusive flavor advantage of organic foods, and about a simple treatment that can increase the flavorfulness of basil and quite possibly other herbs and vegetables.

The second of two recent studies of tomato flavor involves genetic engineering, and offers a scent of tomorrow's tomatoes.

A group of plant scientists in Israel and at Rutgers and the University of Michigan reported their success in transferring a gene from the basil plant into tomato plants. This particular gene diverts molecules in the pathway toward becoming the red pigment lycopene, and sends them instead onto the pathway that generates aroma molecules. The engineered tomato plants produced fruits that were paler than usual, but also had a stronger aroma and smelled distinctly of perfume, rose, geranium, and lemongrass. More than half of a panel of taste testers preferred the engineered tomato to its unengineered parent.

This experiment may be a harbinger of things to come, a new era of plant modification in which flavor combinations once created by cooks will be re-created--or precreated--by breeders in the plants themselves.

Here are a couple of interesting details to add to the story of olive oil's back-of-the-throat, peppery pungency.

In 2003, a research group at Unilever reported on the sensory effects of several of the phenolic compounds found in olive oil, including the cough-inducing substance later named oleocanthal. Oleuropein, the phenolic compound that makes the fruit of the olive bitter, is water-soluble rather than fat-soluble, so it doesn't get transferred into the oil when the fruit is pressed. But a number of oleuropein relatives do end up in the oil, and the Unilever researchers tasted them in pure form. They found these compounds to contribute mainly bitterness and drying astringency, along with some numbing, cooling, sour, salty, and tingling sensations. Relatives of pungent oleocanthal also taste somewhat astringent and bitter. So an oil rich in phenolics can have a very complex taste and mouthfeel indeed.

Other studies have found that heating olive oil reduces the levels of most phenolic compounds. And pepperiness gradually fades as an oil ages. The balance of flavors in an excellent olive oil is thus temporary and so especially worth savoring when you find it. The deterioration of olive oil is slowed by keeping it cool and protected from light.

Spices and herbs are stimulants. Not necessarily pharmacological, but sensory: they stimulate our senses of taste and smell in foods that are otherwise bland. The human diet must have gotten a little boring when our ancestors first learned to cultivate grains and root crops and began to lean heavily on these starchy staffs of life, after millions of years of eating this and that as hunter-gatherers. So when did humans start spicing up their monotonous new diet? Very early--in the Americas, even before the widespread use of cooking pots, according to a new report on the archaeology of the chilli "pepper." A group of fifteen scientists led by Linda Perry of the Smithsonian Museum of Natural History published their results in this week's Science.

Tomato lovers know that a sprinkling of salt enhances the flavor of even the best field-ripened specimen. Some recent news that bodes well for improved flavor in greenhouse tomatoes: you can enhance tomato flavor by salting the plant as the fruit grows! At the Institute of Vegetable Science in Freising, German scientists grew hydroponic tomatoes in a solution that was 0.1% sodium chloride, about one-thirtieth the salinity of seawater. The plants produced fruits with significantly higher levels of flavorful organic acids and sugars, and as much as a third more vitamin C and beta-carotene (the precursor to vitamin A) and the antioxidant red pigment lycopene. The researchers don’t say whether the tomatoes were saltier than usual. They were smaller, so salting the growing medium may be the hydroponic equivalent of dry-farming, which restricts the availability of water to the plant and the dilution of flavor and nutrients.

Stress on our food plants may be hard for the plants, but good for us. Scientists are now studying the biochemical effects of agricultural practices in great detail, and one consistent finding is that plant stress--from insects, heat, sunlight, water and mineral deficiencies--can induce plants to produce higher levels of antioxidants and other phytochemicals that may be good for human health. Organic agriculture, with no pesticides or mineral concentrates, usually exposes crops to more stress, and its produce is usually higher in phytochemicals. Now, in a study of syrah grapes grown near Chateauneuf du Pape in southern France, French scientists have found higher levels of antioxidant anthocyanin pigments in the conventionally grown crop. They attribute this to the possibility that, because the grapevines were already severely stressed by heat and drought, the spraying of pesticides constituted an additional, chemical stress. If this theory is correct, then pesticides may sometimes contribute more to human nutrition than just higher crop yields and less expensive produce.